/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the OpenSimulator Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Reflection;

using OpenMetaverse;

using log4net;

namespace OpenSim.Framework
{
    // The terrain is stored in the database as a blob with a 'revision' field.
    // Some implementations of terrain storage would fill the revision field with
    //    the time the terrain was stored. When real revisions were added and this
    //    feature removed, that left some old entries with the time in the revision
    //    field.
    // Thus, if revision is greater than 'RevisionHigh' then terrain db entry is
    //    left over and it is presumed to be 'Legacy256'.
    // Numbers are arbitrary and are chosen to to reduce possible mis-interpretation.
    // If a revision does not match any of these, it is assumed to be Legacy256.
    public enum DBTerrainRevision
    {
        // Terrain is 'double[256,256]'
        Legacy256 = 11,

        // Terrain is 'int32, int32, float[,]' where the ints are X and Y dimensions
        // The dimensions are presumed to be multiples of 16 and, more likely, multiples of 256.
        Variable2D = 22,
        Variable2DGzip = 23,

        // Terrain is 'int32, int32, int32, int16[]' where the ints are X and Y dimensions
        //   and third int is the 'compression factor'. The heights are compressed as
        //   "ushort compressedHeight = (ushort)(height * compressionFactor);"
        // The dimensions are presumed to be multiples of 16 and, more likely, multiples of 256.
        Compressed2D = 27,

        // A revision that is not listed above or any revision greater than this value is 'Legacy256'.
        RevisionHigh = 1234
    }

    public class TerrainData
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        private static string LogHeader = "[TERRAIN DATA]";

        private float[,] m_heightmap;
        // Remember subregions of the heightmap that has changed.
        private bool[,] m_taint;

        // legacy CompressionFactor
        public float CompressionFactor { get; private set; }

        // Terrain always is a square
        public int SizeX { get; protected set; }
        public int SizeY { get; protected set; }
        public int SizeZ { get; protected set; }

        // A height used when the user doesn't specify anything
        public const float DefaultTerrainHeight = 21f;

        // Given a revision code and a blob from the database, create and return the right type of TerrainData.
        // The sizes passed are the expected size of the region. The database info will be used to
        //     initialize the heightmap of that sized region with as much data is in the blob.
        // Return created TerrainData or 'null' if unsuccessful.
        public static TerrainData CreateFromDatabaseBlobFactory(int pSizeX, int pSizeY, int pSizeZ, int pFormatCode, byte[] pBlob)
        {
            // For the moment, there is only one implementation class
            return new TerrainData(pSizeX, pSizeY, pSizeZ, pFormatCode, pBlob);
        }

        public float this[int x, int y]
        {
            get { return m_heightmap[x, y]; }
            set
            {
                if (m_heightmap[x, y] != value)
                {
                    m_heightmap[x, y] = value;
                    m_taint[x / Constants.TerrainPatchSize, y / Constants.TerrainPatchSize] = true;
                }
            }
        }

        public float this[int x, int y, int z]
        {
            get { return this[x, y]; }
            set { this[x, y] = value; }
        }

        public void ClearTaint()
        {
            SetAllTaint(false);
        }

        public void TaintAllTerrain()
        {
            SetAllTaint(true);
        }

        private void SetAllTaint(bool setting)
        {
            for (int ii = 0; ii < m_taint.GetLength(0); ii++)
                for (int jj = 0; jj < m_taint.GetLength(1); jj++)
                    m_taint[ii, jj] = setting;
        }

        public void ClearLand()
        {
            ClearLand(DefaultTerrainHeight);
        }

        public void ClearLand(float pHeight)
        {
            for (int xx = 0; xx < SizeX; xx++)
                for (int yy = 0; yy < SizeY; yy++)
                    m_heightmap[xx, yy] = pHeight;
        }

        // Return 'true' of the patch that contains these region coordinates has been modified.
        // Note that checking the taint clears it.
        // There is existing code that relies on this feature.
        public bool IsTaintedAt(int xx, int yy, bool clearOnTest)
        {
            int tx = xx / Constants.TerrainPatchSize;
            int ty = yy / Constants.TerrainPatchSize;
            bool ret = m_taint[tx, ty];
            if (ret && clearOnTest)
                m_taint[tx, ty] = false;
            return ret;
        }

        // Old form that clears the taint flag when we check it.
        // ubit: this dangerus naming should be only check without clear
        // keeping for old modules outthere
        public bool IsTaintedAt(int xx, int yy)
        {
            return IsTaintedAt(xx, yy, true /* clearOnTest */);
        }

        // TerrainData.GetDatabaseBlob
        // The user wants something to store in the database.
        public bool GetDatabaseBlob(out int DBRevisionCode, out Array blob)
        {
            DBRevisionCode = (int)DBTerrainRevision.Variable2DGzip;
            blob = ToCompressedTerrainSerializationV2DGzip();
            return true;
        }

        // TerrainData.GetCompressedMap
        public float[] GetCompressedMap()
        {
            float[] newMap = new float[SizeX * SizeY];

            int ind = 0;
            for (int xx = 0; xx < SizeX; xx++)
                for (int yy = 0; yy < SizeY; yy++)
                    newMap[ind++] = m_heightmap[xx, yy];

            return newMap;
        }

        public TerrainData Clone()
        {
            TerrainData ret = new TerrainData(SizeX, SizeY, SizeZ);
            ret.m_heightmap = (float[,])this.m_heightmap.Clone();
            return ret;
        }

        // This one dimensional version is ordered so height = map[y*sizeX+x];
        // DEPRECATED: don't use this function as it does not retain the dimensions of the terrain
        //     and the caller will probably do the wrong thing if the terrain is not the legacy 256x256.
        public float[] GetFloatsSerialized()
        {
            int points = SizeX * SizeY;
            float[] heights = new float[points];

            int idx = 0;
            for (int jj = 0; jj < SizeY; jj++)
                for (int ii = 0; ii < SizeX; ii++)
                {
                    heights[idx++] = m_heightmap[ii, jj];
                }

            return heights;
        }

        // TerrainData.GetDoubles
        public double[,] GetDoubles()
        {
            double[,] ret = new double[SizeX, SizeY];
            for (int xx = 0; xx < SizeX; xx++)
                for (int yy = 0; yy < SizeY; yy++)
                    ret[xx, yy] = (double)m_heightmap[xx, yy];

            return ret;
        }

        public unsafe void GetPatchMinMax(int px, int py, out float zmin, out float zmax)
        {
            zmax = float.MinValue;
            zmin = float.MaxValue;

            int stride = m_heightmap.GetLength(1);

            int startx = px * 16 * stride;
            int endx = (px + 1) * 16 * stride;
            int starty = py * 16;
            fixed (float* map = m_heightmap)
            {
                for (int i = startx; i < endx; i += stride)
                {
                    float* p = &map[i];
                    for (int j = starty; j < starty + 16; j++)
                    {
                        float val = p[j];
                        if (val > zmax) zmax = val;
                        if (val < zmin) zmin = val;
                    }
                }
            }
        }

        public unsafe void GetPatchBlock(float[] _block, int px, int py, float sub, float premult)
        {
            int k = 0;
            int stride = m_heightmap.GetLength(1);

            int startX = px * 16 * stride;
            int endX = (px + 1) * 16 * stride;
            int startY = py * 16;
            fixed(float* block = _block, map = m_heightmap)
            {
                for (int y = startY; y < startY + 16; y++)
                {
                    for (int x = startX; x < endX; x += stride)
                    {
                        block[k++] = (map[x + y] - sub) * premult;
                    }
                }
            }
        }

/*
 //    that is coded as the float height times the compression factor (usually '100'
        //    to make for two decimal points).
        public short ToCompressedHeightshort(float pHeight)
        {
            // clamp into valid range
            pHeight *= CompressionFactor;
            if (pHeight < short.MinValue)
                return short.MinValue;
            else if (pHeight > short.MaxValue)
                return short.MaxValue;
            return (short)pHeight;
        }

        public ushort ToCompressedHeightushort(float pHeight)
        {
            // clamp into valid range
            pHeight *= CompressionFactor;
            if (pHeight < ushort.MinValue)
                return ushort.MinValue;
            else if (pHeight > ushort.MaxValue)
                return ushort.MaxValue;
            return (ushort)pHeight;
        }
*/

        public float FromCompressedHeight(short pHeight)
        {
            return ((float)pHeight) / CompressionFactor;
        }

        public float FromCompressedHeight(ushort pHeight)
        {
            return ((float)pHeight) / CompressionFactor;
        }

        // To keep with the legacy theme, create an instance of this class based on the
        //     way terrain used to be passed around.
        public TerrainData(double[,] pTerrain)
        {
            SizeX = pTerrain.GetLength(0);
            SizeY = pTerrain.GetLength(1);
            SizeZ = (int)Constants.RegionHeight;
            CompressionFactor = 100.0f;

            m_heightmap = new float[SizeX, SizeY];
            for (int ii = 0; ii < SizeX; ii++)
            {
                for (int jj = 0; jj < SizeY; jj++)
                {
                    m_heightmap[ii, jj] = (float)pTerrain[ii, jj];

                }
            }
            // m_log.DebugFormat("{0} new by doubles. sizeX={1}, sizeY={2}, sizeZ={3}", LogHeader, SizeX, SizeY, SizeZ);

            m_taint = new bool[SizeX / Constants.TerrainPatchSize, SizeY / Constants.TerrainPatchSize];
            ClearTaint();
        }

        // Create underlying structures but don't initialize the heightmap assuming the caller will immediately do that
        public TerrainData(int pX, int pY, int pZ)
        {
            SizeX = pX;
            SizeY = pY;
            SizeZ = pZ;
            CompressionFactor = 100.0f;
            m_heightmap = new float[SizeX, SizeY];
            m_taint = new bool[SizeX / Constants.TerrainPatchSize, SizeY / Constants.TerrainPatchSize];
            // m_log.DebugFormat("{0} new by dimensions. sizeX={1}, sizeY={2}, sizeZ={3}", LogHeader, SizeX, SizeY, SizeZ);
            ClearTaint();
            ClearLand(0f);
        }

        public TerrainData(float[] cmap, float pCompressionFactor, int pX, int pY, int pZ)
            : this(pX, pY, pZ)
        {
            CompressionFactor = pCompressionFactor;
            int ind = 0;
            for (int xx = 0; xx < SizeX; xx++)
                for (int yy = 0; yy < SizeY; yy++)
                    m_heightmap[xx, yy] = cmap[ind++];
            // m_log.DebugFormat("{0} new by compressed map. sizeX={1}, sizeY={2}, sizeZ={3}", LogHeader, SizeX, SizeY, SizeZ);
        }

        // Create a heighmap from a database blob
        public TerrainData(int pSizeX, int pSizeY, int pSizeZ, int pFormatCode, byte[] pBlob)
            : this(pSizeX, pSizeY, pSizeZ)
        {
            switch ((DBTerrainRevision)pFormatCode)
            {
                case DBTerrainRevision.Variable2DGzip:
                    FromCompressedTerrainSerializationV2DGZip(pBlob);
                    m_log.DebugFormat("{0} HeightmapTerrainData create from Variable2DGzip serialization. Size=<{1},{2}>", LogHeader, SizeX, SizeY);
                    break;

                case DBTerrainRevision.Variable2D:
                    FromCompressedTerrainSerializationV2D(pBlob);
                    m_log.DebugFormat("{0} HeightmapTerrainData create from Variable2D serialization. Size=<{1},{2}>", LogHeader, SizeX, SizeY);
                    break;
                case DBTerrainRevision.Compressed2D:
                    FromCompressedTerrainSerialization2D(pBlob);
                    m_log.DebugFormat("{0} HeightmapTerrainData create from Compressed2D serialization. Size=<{1},{2}>", LogHeader, SizeX, SizeY);
                    break;
                default:
                    FromLegacyTerrainSerialization(pBlob);
                    m_log.DebugFormat("{0} HeightmapTerrainData create from legacy serialization. Size=<{1},{2}>", LogHeader, SizeX, SizeY);
                    break;
            }
        }

        // Just create an array of doubles. Presumes the caller implicitly knows the size.
        public Array ToLegacyTerrainSerialization()
        {
            Array ret = null;

            using (MemoryStream str = new MemoryStream((int)Constants.RegionSize * (int)Constants.RegionSize * sizeof(double)))
            {
                using (BinaryWriter bw = new BinaryWriter(str))
                {
                    for (int xx = 0; xx < Constants.RegionSize; xx++)
                    {
                        for (int yy = 0; yy < Constants.RegionSize; yy++)
                        {
                            double height = this[xx, yy];
                            if (height == 0.0)
                                height = double.Epsilon;
                            bw.Write(height);
                        }
                    }
                }
                ret = str.ToArray();
            }
            return ret;
        }

        // Presumes the caller implicitly knows the size.
        public void FromLegacyTerrainSerialization(byte[] pBlob)
        {
            // In case database info doesn't match real terrain size, initialize the whole terrain.
            ClearLand();

            try
            {
                using (MemoryStream mstr = new MemoryStream(pBlob))
                {
                    using (BinaryReader br = new BinaryReader(mstr))
                    {
                        for (int xx = 0; xx < (int)Constants.RegionSize; xx++)
                        {
                            for (int yy = 0; yy < (int)Constants.RegionSize; yy++)
                            {
                                float val = (float)br.ReadDouble();

                                if (xx < SizeX && yy < SizeY)
                                    m_heightmap[xx, yy] = val;
                            }
                        }
                    }
                }
            }
            catch
            {
                ClearLand();
            }
            ClearTaint();
        }


        // stores as variable2D
        // int32 sizeX
        // int32 sizeY
        // float[,] array

        public Array ToCompressedTerrainSerializationV2D()
        {
            Array ret = null;
            try
            {
                using (MemoryStream str = new MemoryStream((2 * sizeof(Int32)) + (SizeX * SizeY * sizeof(float))))
                {
                    using (BinaryWriter bw = new BinaryWriter(str))
                    {
                        bw.Write((Int32)SizeX);
                        bw.Write((Int32)SizeY);
                        for (int yy = 0; yy < SizeY; yy++)
                            for (int xx = 0; xx < SizeX; xx++)
                            {
                                // reduce to 1cm resolution
                                float val = (float)Math.Round(m_heightmap[xx, yy],2,MidpointRounding.ToEven);
                                bw.Write(val);
                            }
                    }
                    ret = str.ToArray();
                }
            }
            catch {}

            m_log.DebugFormat("{0} V2D {1} bytes", LogHeader, ret.Length);

            return ret;
        }

        // as above with Gzip compression
        public Array ToCompressedTerrainSerializationV2DGzip()
        {
            Array ret = null;
            try
            {
                using (MemoryStream inp = new MemoryStream((2 * sizeof(Int32)) + (SizeX * SizeY * sizeof(float))))
                {
                    using (BinaryWriter bw = new BinaryWriter(inp))
                    {
                        bw.Write((Int32)SizeX);
                        bw.Write((Int32)SizeY);
                        for (int yy = 0; yy < SizeY; yy++)
                            for (int xx = 0; xx < SizeX; xx++)
                            {
                                bw.Write((float)m_heightmap[xx, yy]);
                            }

                        bw.Flush();
                        inp.Seek(0, SeekOrigin.Begin);

                        using (MemoryStream outputStream = new MemoryStream())
                        {
                            using (GZipStream compressionStream = new GZipStream(outputStream, CompressionMode.Compress))
                            {
                                inp.CopyStream(compressionStream, int.MaxValue);
                                compressionStream.Close();
                                ret = outputStream.ToArray();
                            }
                        }
                    }
                }
            }
            catch {}

            m_log.DebugFormat("{0} V2DGzip {1} bytes", LogHeader, ret.Length);
            return ret;
        }

        // Initialize heightmap from blob consisting of:
        //    int32, int32, int32, int32, int16[]
        //    where the first int32 is format code, next two int32s are the X and y of heightmap data and
        //    the forth int is the compression factor for the following int16s
        // This is just sets heightmap info. The actual size of the region was set on this instance's
        //    creation and any heights not initialized by theis blob are set to the default height.
        public void FromCompressedTerrainSerialization2D(byte[] pBlob)
        {
            Int32 hmFormatCode, hmSizeX, hmSizeY, hmCompressionFactor;

            using (MemoryStream mstr = new MemoryStream(pBlob))
            {
                using (BinaryReader br = new BinaryReader(mstr))
                {
                    hmFormatCode = br.ReadInt32();
                    hmSizeX = br.ReadInt32();
                    hmSizeY = br.ReadInt32();
                    hmCompressionFactor = br.ReadInt32();

                    CompressionFactor = hmCompressionFactor;

                    // In case database info doesn't match real terrain size, initialize the whole terrain.
                    ClearLand();

                    for (int yy = 0; yy < hmSizeY; yy++)
                    {
                        for (int xx = 0; xx < hmSizeX; xx++)
                        {
                            float val = FromCompressedHeight(br.ReadInt16());
                            if (xx < SizeX && yy < SizeY)
                                m_heightmap[xx, yy] = val;
                        }
                    }
                }
                ClearTaint();

                m_log.DebugFormat("{0} Read (compressed2D) heightmap. Heightmap size=<{1},{2}>. Region size=<{3},{4}>. CompFact={5}",
                                LogHeader, hmSizeX, hmSizeY, SizeX, SizeY, hmCompressionFactor);
            }
        }

        // Initialize heightmap from blob consisting of:
        //    int32, int32, int32, float[]
        //    where the first int32 is format code, next two int32s are the X and y of heightmap data
        // This is just sets heightmap info. The actual size of the region was set on this instance's
        //    creation and any heights not initialized by theis blob are set to the default height.
        public void FromCompressedTerrainSerializationV2D(byte[] pBlob)
        {
            Int32 hmSizeX, hmSizeY;
            try
            {
                using (MemoryStream mstr = new MemoryStream(pBlob))
                {
                    using (BinaryReader br = new BinaryReader(mstr))
                    {
                        hmSizeX = br.ReadInt32();
                        hmSizeY = br.ReadInt32();

                        // In case database info doesn't match real terrain size, initialize the whole terrain.
                        ClearLand();

                        for (int yy = 0; yy < hmSizeY; yy++)
                        {
                            for (int xx = 0; xx < hmSizeX; xx++)
                            {
                                float val = br.ReadSingle();
                                if (xx < SizeX && yy < SizeY)
                                    m_heightmap[xx, yy] = val;
                            }
                        }
                    }
                }
            }
            catch (Exception e)
            {
                ClearTaint();
                m_log.ErrorFormat("{0} 2D error: {1} - terrain may be damaged",
                                LogHeader, e.Message);
                return;
            }
            ClearTaint();

            m_log.DebugFormat("{0} V2D Heightmap size=<{1},{2}>. Region size=<{3},{4}>",
                            LogHeader, hmSizeX, hmSizeY, SizeX, SizeY);

        }

        // as above but Gzip compressed
        public void FromCompressedTerrainSerializationV2DGZip(byte[] pBlob)
        {
            m_log.InfoFormat("{0} VD2Gzip {1} bytes input",
                            LogHeader, pBlob.Length);

            Int32 hmSizeX, hmSizeY;

            try
            {
                using (MemoryStream outputStream = new MemoryStream())
                {
                    using (MemoryStream inputStream = new MemoryStream(pBlob))
                    {
                        using (GZipStream decompressionStream = new GZipStream(inputStream, CompressionMode.Decompress))
                        {
                            decompressionStream.Flush();
                            decompressionStream.CopyTo(outputStream);
                        }
                    }

                    outputStream.Seek(0, SeekOrigin.Begin);

                    using (BinaryReader br = new BinaryReader(outputStream))
                    {
                        hmSizeX = br.ReadInt32();
                        hmSizeY = br.ReadInt32();

                        // In case database info doesn't match real terrain size, initialize the whole terrain.
                        ClearLand();

                        for (int yy = 0; yy < hmSizeY; yy++)
                        {
                            for (int xx = 0; xx < hmSizeX; xx++)
                            {
                                float val = br.ReadSingle();
                                if (xx < SizeX && yy < SizeY)
                                    m_heightmap[xx, yy] = val;
                            }
                        }
                    }
                }
            }
            catch( Exception e)
            {
                ClearTaint();
                m_log.ErrorFormat("{0} V2DGzip error: {1} - terrain may be damaged",
                                LogHeader, e.Message);
                return;
            }

            ClearTaint();
            m_log.DebugFormat("{0} V2DGzip. Heightmap size=<{1},{2}>. Region size=<{3},{4}>",
                            LogHeader, hmSizeX, hmSizeY, SizeX, SizeY);

        }
    }
}